Artificial haptic perception neuron based on VO2 volatile memristor
In a biological sensory nervous system, the mechanoreceptors are responsible for sensory information transduction. When the external stimuli exceed the mechanical threshold of the mechanoreceptors, sensory information is being coded through an action potential at a certain frequency.[38, 39] To mimic the biological activity from mechanoreceptors, the spiking response due to a haptic event, we integrated the piezoresistive sensor with a VO2 memristor to emulate the haptic perception as an artificia mechanoreceptor. Given the dependence of the output frequency of VO2 oscillation neuron on the load resistor (Figure 2b,d), the haptic perception function can be achieved by replacing the fixed RL with a piezoresistive sensor. Figure 4a shows a schematic diagram of the artificial haptic perception neuron using VO2 volatile memristor and a commercially available piezoresistive sensor (the entire experimental setup is shown in Figure S7, Supporting information). Figure 4b shows the I–V curves of the piezoresistive sensor under different pressures, showing different resistance state in response to pressure/weight inputs (from 20 to 700 g). Moreover, Figure 4c summarizes the resistance response of the piezoresistive sensor under different pressures/weights. The stability and thermal characteristics of the piezoresistive sensor are further shown in Figures S8 and S9, Supporting Information. It can be clearly seen that the resistance gradually decreases as the pressure increases. This characteristic can be generalized by a power function: